Telephone-exchange system



c. L. GOODRUM TELEPHONE EXCHANGE SYSTEM Aug. 21, 1923.

Filed Sent. 30, 1920 Wye/#0,: Char/e5 L. Good/um Af/i Patented Aug. 21, was.

CHARLES L. GOOIDRUIE, 6F NEW YORK, Ii. Y., ASSIGNDR TS 'WESIEEN ELECTRIC 001% PANY, Irroonronnrnn, or new 1.,

A COBPORATEON OF NET/V YORK.

TELEPHONE-EXCHANGE SYSTEJZI.

Application filed September 30,

To all whom it may, concern:

Be it known that I, Cnnnnns L. Goonnuir, a citizen of the United States, residing at New York, in the county of New York, State of New York, have invented certain new and useful Improvements in Telephone Exchange'Systems, of which the following is a full, clear, concise, and exact descrip tion. 7

This invention relates to improvements in telephone systems and has particular reference to a selector switch used in systems employing machine switching. It has been customary, in selector switches of known construction, to effect the changeover operations by theuse of slow-releasing relays.

An object or" the present invention is to provide improved means for eliminating the use of slow relays in the operation of a selector switch.

In accomplishing the'above object, the in- 'vention provides two switching devices which cooperate to transmit impulses for.

operating the switch, one of said devices be ing responsive to the connection 01": a calling 1 substation to the selector's witch and to impulses transmitted from said substation, while the other device 1S responsive only to .the movement-of the variably operable impulse sender from its normal position when actuated to transmit said impulses. The drawing diagrammatically illustrates a preierredembodiment of a circuit arrangement for carrying out the invention.

It i believed that the invention will be best understood from the following detailed description of operation. I 7

When a subscriber at substation 1 removes his receiver from its switchhook to initiate a call, the line'switch, conventionally shown at 2 and which may be of any desired construction, is operated to seek the terminals of a trunk associated with an idle selector switch Uponthe engagement of the brushes of the line switch with the terminals 8, and 5 of an idle switch, a circuit is establish'ed extending from grounded battery through theleft-han'd winding or dii'lere n V tial line relay 6, side switch wiper 7 in position 1, terminal 1, brush 8, the apparatus at substation 1, the impulse springs oi the variably operable sender 10, brush 11, terminal 3, the side switch wiper 12 in position 1, the winding of pulsing relay 13, and

1929. Serial No. 413,856.

the righ -hand winding of relay 6 to ground. Relay 6 is arranged so as not to, respond to the current flowing through this metallic circuit, but relay. 15 is energized to open its normal contacts.

The subscriber at substation 1 now pro coeds to manipulate the impulse sender lfl to transmit impulses COIIGSPOIlCliIlg to the first digit of the required number, and upon the initial movement of said sender from its normal position the off normal springs 14- of the sender are closed to establish a circuit from a ground branch including a resistance through said springs 14, the substation apparatus, brush 8, terminal l,side switch wiper 7, and the left-hand winding of relay 6 to grounded battery. Differential relay (3 responds to current flowing through. this circuit, and, in closing its frontcontact, prepares a circuit for the primary stepping magnet 15 of the selector switch. The return movement of the sender 10 causes the alternate opening and closing of the impulse spring 9 to interrupt the line circuit extending through the pulsing relay 13, which responds to each interruption. The resistance connected to spring 1 1 prevents the short-circuiting of the impulse relay 13. Inasmuch as relay 6 remains energized as lone; as the sender is oil normal, a circuit will now be established, upon each deenergization of relay 13, extending from ground through the armature and frontcontact of relay 6, the inner armature and contact of relay 13, the side'switch wiper 16 in position 1, and the winding of the primary stepping magnet 15 to grounded battery. he magnet 15 operates in the well known manner to step the brushes 1?, 1S and 19 over the terminals of trunks to which the switch has access. Upon the initial energization of relay 6, a circuit is established for escape in agnet 20, extending from grounded battery through the winding oi? said magnet, the side switch wiper 21 in position. 1, and the front contact and armature of relay 6 to ground. ltlagnet 2O energizes but the usual escape inecha ism is arranged to prevent movement of. the side switch wipers from position 1 until said magnet releases. lVith the termition of series o impulses transmitted irom the substation, sender 10 is again 'rcstored to normal, opening the off normal springs 1 1 which causes" the deenergization of relay 6. Relay 13, however, remains through the winding,armature and contact.

of said i'nagnet, the armature and contact oi' magnet 20, and the side switch wiper in position 2, to ground. Magnet 22 operates the switch in its secon dary or trunk hui'iting movement and causes the brushes thereof to engage the terminals of the selected glOHP of trunks in seeking an idle one in said group. The idle condition of a trunk is denoted by ground upon the test terminal 24:, and upon the engagement of the brushes oi' the switch with the terminals of the first idle trunk encountered, a circuit is established for escape. magnet .20, extending through the side switch wiper 21 in position 2, and brush 19, to ground on the test ter minal 2a. The escape mechanism of magnet 20 is, in this instance, adjusted to move the side switch wipers oi? the switch "from position 2 to position 3 upon the energization oi magnet 20. It is thus apparentthat the instant an idle trunk is encountered, magnet 20 energizes to permanentlyopen the self-interrupting circuit of magnet 22 whereupon, the switch will be brought to rest upon the tcrniinalsot' the seized trunk.

It at any time before the, movement of the side switch wiper from position 2, the subscriber at substation 1 should abandon the call, the circuit for pulsing relay 13 will be opened at the switch hook contacts and this relay will release. W'ith relay 6 in its normal condition a circuit will. then be established for the release magnet 25, extendingfrom rounded battery through the winding oil: this magnet, the side switch wiper 26 in positions 1 or 2, the oil normal contact 27, which closed upon, the initial movement of the switch from its normal position, the back contact and outer armature of. relay 13, and the back contact and armature of relay 6 to ground. Magnet 25 is energized and closes a locking circuit for itselt through its contact and armature, whereby the switch is restored to normal, whereupon the oil normal contact 27 will be opened and the magnet 25 released.

The llIOVPITIPDlL of the side switch wipers oil the switch into position 3, by the second energization .o i'nagnet 20 extends the telephone line ot substation 1, through to the next succeeding switch which it desired ma he of t ie same construction and arrangement as the one shown in the drawing. The trans'- mission of: further impulses from substation 1 operates any succeeding switches to tend the calling Slll3S(lll3Bl",S line to the called line, in amanner well understood.

The

ground from thearmature and back cont-act of relay 6 is removed from the multiple test terminal 5 of the trunk-associated with the seized switch and causes the same to test busy to any other line switch; 7

At the termination of the conversation, the switches, succeeding the one shown inv the drawing, are released in any manner well-known in the art by the replacing of the receiver upon its switch hookv at thecalled substation. Ground being agaln' applied to x the test terminal 2%, engaged by brush it),

causes the energization of the release magnet 25, through the side switch wiper 26 in po sition 3. The release magnet is again energized and locked to return the switch to normal, as previously described. What is. claimed is: o V 1. In a telephone system, a variably ops erable impulse sender, a selector switch, means responsive to impulses from said sender for operating said switch, and means consisting of only two relays at said selector switch for transmitting the impulses from said sender to said operating means, oneoi said relays being responsive only to the movement of said sender from its normal position. V Y 1 2. In a telephone system, a variably operable impulse sender,.a selector switch, means responsive to impulses from said sender for operating said switch, and meansconsisting of only two relays at said selector switch for transmitting the impulses. from said sender to said operating means, one of said relays being unaffected by the seizure of said Iselectorswitch.

8. In a telephone system, avariably operable impulse sender, a selector switch, means responsive to impulses from said sender for operating said switch, and means consisting of only two relays operable to transmit impulses tromsaidsender to said operating means, one of said relays being operated only while the sender is oil normal.

4i. In a telephonesyste'm, a telephone line, a variably operable impulse sender, a selector switch for extending said line, means for operating said switch, a switching device at said switch responsive to theinitia'tion of a call on saidline and to impulses transmitted by said sender-for controlling the operafor operating said switch, a pulsing relay at said switchresponsiveto the initiation of a call on said lineand to impulses transmitted by said sender for controlling the operation of said operating means, and a differential relay cooperating with said pulsing relay and responsive only to the movement of said sender from its normal position. a

6. In a telephone system, a telephone line,

a variably operable impulse sender, a selector switch for extending said line, means for operating said switch, a pulsing relay at said switch responsive to the initiation of a call on said line and to impulses transmitted by said sender for controlling the operation of said operating means, and a differential relay in series with said pulsing relay and operable only when said sender is moved from its normal position.

In witness whereof, I hereunto subscribe my name this 27th day of September A. D.

CHARLES L. GOODRUM. 

